To those that have been in the cab when runing at normal sped and at abnormal speed.
A steam locomotive can go as fast as the boiler pressure, valve gear and side rods will allow.
I have been around locomotives rated at 30 do close to 60mph.
The locomotives when operating at over the normal speed tend to start to buck and rear up when the track is not really in good shape, which results in quite a ride.
A good engineer that knows the line he or she is running on can actually do the job quite well as a good strong roadbed can make the Difference.
Knowing where you can make time and where not to run her out is the real example of a good hogger.
I have worked with several old Hoggers that could make time and not even spill a glass of water doing it.
I know several Hogger's that are speed hounds and that results in taking too many chances, which can cat up with them very quickly.
I can say from observation that most of the Rio Grande Narrow Gauge Engineers past and present are the Good Hand's, as the Train Accidents List is very small, and not of serious incidents.
Stephen